Apparatus for controlling gaseous atmosphere



July 11, 1944. BARBER 2,353,538

APPARATUS FOR CONTROLLING GASEOUS ATMOSPHERE Filed April 23; 1940 3 Sheets-Sheet l hJ f0 I '3 j i 3 Jifor/fkj y 1, 1944. H. H. BARBER 2,353,538

APPARATUS FOR CONTROLLING GASEOUS ATMOSPHERE Filed April 25, 1940 :5 Sheets-Sheet 2 July 11, 1944.

H. H. BARBER Filed April 25, 1940 3 Sheets-Sheet 3 Patented July ll, i944 3 2,353,533

UNITED STATES PATENT orrica APPARATUS GAIEIOUS V i lerveylliarbensal'anhlflnn.

mllflflfll A'l'll :1, 1m, N0. 831.301

Chill. (Cl-H71) This invention relates to a method and anproperties of carbon dioxide and air for conparatus tor the" preservation of articles oi iood r ing said last mentioned means. and particularly to a method and apparatus of These and other objects and advantages of regulating and maintaining an atmosphere conthe invention will be fully set forth in the foltaining a. definite proportion of carbon dioxide lowing description made in connection with the gas in a storage chamber for articles of food. momplnylng drawings in w i h ke reference It has be discovered um; atmqwherq; hay. characters refer to similar parts throughout the ing certain proportions of carbon dioxide gas Winwhiehhave remarkable qualities for the preservation 1 i5 somewhat dimmatic View Of of articles of food. Meat can be preserved in ml of 119mm"! "led;

good condition in an atmosphere of air and car- 2 13 a View filmed scale 2 hon dioxide containing from 13 to 'go of a portion of the apparatus illustrated in Fig. 1;

the latter. The results obtained are even better a mimetic View of other form than obtained by careful refrigeration. Vege- 0f apparatus which mirhtbeused:

tables can likewise be preserved with an atmos- 4 is a View in side elevation of a m ifi d phere or 1m 2 t 6 percent of carbon dioxide form of apparatus. some parts being broken away while fruits" may be preserved in an atmos h and others shown in vertical section;

of from 3% 10 percent u flo can m 5 is a. plan view of the device shown in be preserved in a remarkable manner in an atmgsphere of carbon xid d roses in pal so: 18 a horizontal section taken substanticular can be kept for quite a long period with me 3 l. of 4 as indicated by the n the petals still in firm and attached condition.

a Fig. 7 is a partial view similar to Fig. 4 showing F1811 can be Preserved without loam the flavor theparts in different positions;

of fresh fish. One obiectionto preserving fish m cold on is that the nave-r a may lost. 8 is a view similar to Fig. 4 showing the Wniie it is fairly easy to secure an atmosphere g f jfi m and p of carbon dioxide. heretofore no successful or practical means has been produced for controlgf g z' am? View M a 1mm,

ling such an atmosphere and maintaining the g tmgs p 'e w the dellred Percenu" w l fifi fifm n fie mifir' fi fim ii mgfi :1 oz e.

I It is an object of this inventicn to provide a- 3?:38? fggfififigigfig; and pphmtus by .means which m of air and carbon dioxide with a definite proatmoephere 011m definite as. portion of the latter. Said chamber will be used P01151011 dmxme may be unnamed v for the storage of articles of food or other artilnl conditionelse to be preserved, such as meat. vegetables,

It is another object of the invention to provide mats. milk products and fl wers etc. In the a st rage chamber for articles of food ha inl mbodiment Of the invention illustrated in Figs. therein an atmosp e e or ai with a definite 40 land 2, a balance is provided comprising a base portion of carbon dioxide and means for 1115111- I: having 1 central vertically extending standmning 4 tmogphere with such pr p ard lid with a bearing I2b at its top having a actuated by the diil'erence in p pe s of V-shaped recess therein. A balance beam lzc bon dioxide and air-or other 8 liih er t n is provided with members lid having edged carbon dioxide. I blades secured thereto, the edges of which seat It is still another object of' he nv n to in the recess in member 12b. A screw |2e ex pr vi a method and pparatus for resul na tends centrally from the beam i2c and has adand maintaining an atmospher nta n s .iustable thereon a weight I2! for varying the definite proportion of carbon dioxide in a storage sensitivity of the balance and decreasing the chamber for articles of food comprising the use so pendulum t A ta r I: extends of r e of carbon dioxide :88, me s tically adjacent one end of the base I! the same meeting said source of gas with said chamber. having forwardly extending proiectionjsila and electrically operated means for operating s lib between which one end of balance beam l2c last mentioned means and means disposed in is disposed. An electrical contact i4 is carried d chamber and actuated by the diiierence in 66 on the upper side of member Ila and a thumb screw I5 extends through portion |3b being ad- Justable therein, the lower end of which forms a stop for beam I20. Beam |2c carries adjacent its end and at the lower side thereof an electrical contact member I6 adapted to engage with contact member H. A weight |2g has a screw I2h secured thereto which is threaded into and adjustable in one end of beam 120 so thatsaid weight may be used to balance said beam. A container shown as of spherical form is provided and this preferabl will be made of thin material such as glass or metal. Container I! alsohas secured thereto a screw Ila threaded into one end of beam I20 and adjustable therein.

for the purpose of balancing beam |2c.- Beam 12c is provided with a plurality of notches I22 and said beam may be graduated in connection with said notches to indicate percentages of carbon dioxide in the atmosphere. member I8 is movable on beam I20 and may be disposed in any one of the notches I22. A bind- An indicating ing post I9 is secured in base I2, which base preferably is of nonconducting material and said bindin P st is connected by an electrical conductor 20 to the standard'l3 which preferably is of metal so that binding post I9 is connected to contact I4. Another binding post 2| is secured in base I2 and connected by an electrical conductor 22 to standard IZa which is also preferably of metal as is beam I2c. Binding post 2| is thus connected to-the contact member I6. Electrical conductors 23 and 24 extend from binding posts l9 and 2| to the outer side of the chamber within wall I I and are respectively connected to binding posts or contacts 25 and 26 forming the grid contacts of a vacuum tube I21, such as now commonly used in radio receiving sets. Said tube is shown as havin a plate Illa connected through a resistance 28 to contact member 25. While the value of resistance 28 might vary, in one embodiment of the invention in practice a resistance of one-fifth of a megohm has been used. Tube 21 has a grid 2'Eb therein which is connected to contact member 25. Tube 21 also has a filament 270, one end' of which is connected through a resistance 28 to a contact member or binding post 30. While resistance 29'might be varied, in one embodiment of the invention in practice a resistance of 350 megohms has been used. The other end of filament 210 is connected through a resistance 3| to a contact or binding post 32. While resistance 3| might be varied, in practice a resistance of 100 megohms has been used successfully. A conductor 33 is connected to grid 21b and conductor 3| and extends through a resistance :34 and to one contact 35a of a mercury tube switch 35. Another contact member 36 of tube 21 is connected b a conductor 37 to the other con tact 35b of switch 35. The plate Z'Ia is connected by a conductor 38 to one end of the winding of a small solenoid 38, the other end of said winding being connected by a conductor 50 to a contact or binding post til forming part of the plate circuit of tube2l. A conductor IIa connects binding posts and 4|. Solenoid 39 has a plunger core 39a connected by a link 22 to an arm 350 of switch 35, said arm being oscillatable about a pivot member 43 carried in a bracket 54 secured to a base member 45 on which solenoid 39 is mounted. An upright post or bracket 56 and BI extend respectively from contacts 36 and 4| and are connected to the contacts of a solenoid valve 52. Solenoid valve 52 is disposed in or has secured thereto the communicating portions of a conduit 53 which extends through wall II and has an open end delivering into the chamber within wall The other end of conduit 53 extends to an outlet valve 54 secured to the top of a metal cylinder 55 containing carbon dioxide under pressure. Cylinder 55 is of the usual commercial form in which carbon dioxide under great pressure is carried. A reducing valve 56 is disposed in the conduit 53, the same being shown as having thereon a gauge 56a. A pair of conductors 51 and 58 are connected respectively to the contacts 30 and 32 which are connected to the filament 210. 110 volt alternatin current will be supplied to conductors 57 and 58 from any suitable source of supply as from an ordinary electrical socket.

In the method of regulating and maintainin the atmosphere in the chamber within wall II the balance carried on base I2 will be set so that it will be balanced with the desired percentage of carbon dioxide in the atmosphere. The valve 54 remains open and the carbon dioxide from cylinder 55 passes through conduit 53, through the reducing valve 55 to valve 52. When current is supplied through conductors'eil and 5| valve 52 is open and when no current is passing said valve is in closed position. Assuming that the atmosphere in the chamber within wall II has not yet reached the desired content of carbon dioxide the apparatus will be in the posi tion indicated in Fig. 1. Container I! will not be lifted to close contacts I5 and It. The plate circuit of tube 2] will be closed and current will be supplied to solenoid 33. Resistance 34 in the conductor 33 connected to grid 2Tb with contacts 25 and 25 not connected prevents flow of the current through the grid. Current thus flows from line 58 to contact 32 and filament 21c thence to' plate 27a and through conductor 38 and solenoid 39 to contact 8|, thence through conductor 4|a to contact 35 and 1ine.5|. Thus solenoid 39 will be energized and mercury switch 35 will be tilted to closed position. A circuit is then closed through contacts 50 and 5| controlled by switch 35 and solenoid valve 52 is opened. Carbon dioxide may now fiow into the chamber within wall II. When the desired content of carbon dioxide is attained in the atmosphere, container H, which contains air or a gas much lighter than carbon dioxide, will be raised, lowering the other end of beam He and engaging contacts it and I6. This will connect conductors 23 and 24 and thus contacts 25 and 26. With contacts and it thus connected a bias is put on grid 21b and the current now will flow from filament 2'50 to the grid21b and the flow of current to the plate 2 7a will be discontinued. Resistance 28 is a two million ohm resistance and there is not enough current flowing therethrough or through the above mentioned circuit to operate solenoid 39. Solenoid 59 will be deenergized and spring i will swing switch 35 to open position. The circuit through conductors 50 and 5| is now opened and valve 52 is closed. The supply of carbon dioxide to the chamber is now out off and the atmosphere in said chamber now contains the desired percentage of carbon dioxide. Should some of the carbon dioxide leak out or should the percentage of carbon dioxide in the atmosphere decrease, container IE will move downward, separating contacts It and I 6. This will open the extends into said connection between conductors II and 24 and contacts 2| and 20, and current will again flow from line II to iilament 210. from filament 210 to and through plate 21a and through solenoid II thus actuating solenoid N, thusmoving switch "to closed position and again actuating valve H to open the same and permit carbon dioxide to flow into the chamber. The amount of current flowing in the grid circuit or tube 21 which includes contacts I and It is very small so that there is no appreciable'sparking at contacts is and Il. With the described method and apparatus for regulating and maintaining the desired percentage of carbon dioxide in the atmosphere the said percentage can be regulated with in very small limits. The regulation isver accurate and as above stated the atmosphere can be regulated withinvery small limits.

In the method and apparatus above described the regulation of the atmosphere is secured by actuating a member in the chamber by the difierence in density between carbon dioxide and air or some lighter gas. In the modification shown in Fig. 3 an apparatus is indicated which may be actuated by the diflerence in thermal conductivity between carbon dioxide and air or some lighter gas. In Fig. 3 an electrical apparatus comprising the well known Wheatstone bridge is shown." This comprises the conductors 60 and I at one side of the bridge and conductors 62 and I at the other side of the bridge. In the usual construction of such abridge fixed resistances II are disposed in three of said conductors, such as 60, ii and 62 and a variable resistance is disposed in the other conductor. Current is supplied to the opposite ends of the bridge at the junction ,of conductors G and 62 and the junction of conductors SI and 63. This is supplied from a battery H or other suitable source of current. An ammeter 85 is shownin conductor H which supplies current to the bridge and an ad- Justable resistance 81 is also shown in said conductor. A conductor Bl extends across the central part of said bridge and a tube 68 is disposed in the conductor or leg 82. The tube 69 will contain air or some lighter gas and may be sealed. A resistance 1' formed of very line wire will be disposed in tube 89 and in conductor 82 which tube. Another tube H is disposed in the conductor or leg 63 and a resistance I2 formed of fine wire will be disposed in tube II and in conductor 83 which extendsinto said tube. Tube 12 will be open as indicated by the openings Ila so that the atmosphere in the chamber within wall H may circulate freely therein. An adiustable resistance I3 is disposed in conductor 6| as is also the winding oi a small solenoid H which will operate a smallmercury tubeswitch 15. With the described arrangement and the apparatus disposed in the chamber within wall it the same will operate as follows:

Resistance 13 will be adjusted so that the bridge will be balanced when or the desired percentage of tained in the atmosphere. No current will then flow through conductor 88 or solenoid 14 and switch 15 will be maintained in open position. Should the percentage of carbon dioxide now in crease there will bea diflerence in the gas entering tube H and this will have a different thermal conductivity. In other words, there is now enough carbon dioxide present so that heat will be conducted away from member 12 varying its resistance enough to unbalance the Wheatstone bridge. The resistance of wire 10 in tube 69 will not be carbon dioxide is atup tothe point when,

and switch 15 affected by the atmosphere in the chamber tube II is closed. The resistance 01' member I! will be varied unbalancing the bridge so that current will flow through conductor II. This will operate solenoid H and move switch "to closed position. The conductors 2| and 22 shown in Fig. 1 will, when the apparatus shown in Fig. 3 is used, be connected to switch 15. Switch 15 will thus act to. clos the grid. circuit of tube 21 and the supply of carbon dioxide to the chamber will be shut oil'.- Should the percentage of carbon dioxide decrease the bridge would again be balanced and current would cease to flow through to open position. The grid circuit of tube 21 would beopened and as above described carbon dioxide would again be supplied to the chamber. The desired percentage of carbon dioxide would thus be accurately maintained. I

Referring to Figs. 5 to 9', another forlnoi the invention is shown. In' this form the arrangement shown in Fig. 3 is used in the chamber which is supplied with carbon dioxide. The conductors ll shown in Fig. 3 are shown inFlg. 9 and these conductors are connected to the terminals of a galvanometer 80 having the usual oscillating needle II, the upper end Ola of which acts as a pointer and cooperates with a scale 82 carried on a casing or housing member graduated from a central zero point in both directions. The galvanometer 80 is of the usual construction comprising a magnet 80a and the details thereof need not be further described; Needlell adjacent its upper end is equipped with a sleeve or bushing N. This bushing in the movement of needle 8! moves closely adjacent an abutment form of a wire.

member 85 illustrated as in the which extends in arcuate form II and has its ends extending bent at right angles, the same being secured in lugs "a of a frame member 86 of U-shape iorm surrounding magnet 80a. Said ends of member ii are engaged and held in place by screws 1|. Frame 85 comprises a plate-like portion 80b overlying the magnet lfla and'portion "b has forwardly projecting arms 860 which are connected to and support a cylindricalportion lid. Portion "d has a reduc'edterminal end oi cylindrical form which fits into the open end of and abuts a bushing 81 illustrated as secured in the lower part of the housing member 83. Screws ll extend outwardly from opposite sides of portion "d and secure thereto a ring 89. Ring 89 is oscillatable about the common axis of screws 88. A member 90 surrounds ring I9 and is movable thereabout and about the axis of said ring and portion lid. The member 90 at its lower portion is formed as a worm wheel segment 90a. A screw or worm 8i cooperates with the portion 90a meshing therewith and carries a handle portion Ola shown as having a knurled cylindrical end.

adjacent needle downwardly and A thin plate 92 is secured to ring tis'by screws to and overlaps a member and portion Md so that member to is held in place on ring 8%. It

.will be noted as shown in Figs. 9 and that portion lid is cut away at its upper side to form an opening through which needle passes. Member 90 has an upwardly projecting arm 90b to which is secured by rivets dd a pair of contact springs 95 and 93. Springsilfi and 96 respectively carry contacts 81 and 98 adapted to engage with each other and spring 95 is continued upwardly in an offset portion 95a for a purpose to be later described. Springs 95 and 98 are carried between 83. Scale I! is i tained in and controls a conduit I41.

of a shape similar to member I04 and having a top arcuate surface extending parallel to the arcuate top portion of member 00 and forming a continuation of the arcuate top portion of member I04. Member"! is also pivoted at its bottom portion to member 44 by a screw I00 passing through a suitable lug on member 00. A pair oi spring or resilient bars I01 and III are provided carried are inalinement with member Ill. Bars I01 and Ill carry contact members Ill and II! normally separated but adapted to be brought into engagement as-will be later'described. Members I04 and I00 are separated a short distance so that there is a space between said members, which space is too narrow for the entrance of sleeve 04.

A small electric motor Iii is mounted upon the frame", being carried by a bracket II1 seated on the top oi'trame l4, said-motor being secured by screws IIO. Said motor is shown as having terminals III to which are connected the usualconductors 12 0 which will extend to some suitable source or current. The armature shaft of motor H0 is connected to a reducing mechanism such as a worm and worm wheel, the latter being connected by shaft I22 to a disk I23. Disk I 23 has depending therefrom a pin I24. Pin I24 is disposed In the plane ot'a lever arm I25a of a lever I oscillatably mounted upon a stud I20 secured in plate 00b and having a nut I21 thereon. Lever I20 has another arm Ib iormed as a-vertical plate, the

outer surface of which is adapted to engage with roller I02 in the movement of lever I20. A tensile coiled spring I21 has one end secured to I by member II and at one side thereof so that they in: I440 to contact 00. Relay I40 has an armature I400 pivoted at I42, said armature having connected thereto alight spring I40 anchored at its other end to a stationary portion I406 oi relay I40. Armature I40c carries a contact I4le normally in engagement with a contact I44. A conductor I40 extends from contact I44 to a magnetic or solenoid valve I48 which is con- Another conductor I40 extends from valve I40 to a'source of. current I 40 and a conductor. I00 extends from source of current I40 to armature I400, conductor IIO having therein a switch Iii. A conductor I52 extendsfrom'contact I 00 to one end of a winding I40b on relay M0 and a conductor III extends from the other end of winding I40b to a source oi current I54. A conductor I60 extends irom source I54 to contact IIO. Conduit I41 extends from valvev I40 to a reducing valve Ill and a conduit I41a extends from valve I 00 to the discharge valve I00 or a cylinder Ill adapted to contain carbon dioxide under pres- Big-:9. A pressure gauge "I is connected to valve The operation of the device shown in Figs. 4 to 9 is as follows:

Using the bridge shown in Fig. 3 resistance 13 will be'adiusted so that the bridge will be balanced with an ordinary atmosphere 01' air in the chamber within wall I03. No current will then flow through conductors 0p and through galvanometer 00. The discharge valve I59 on-the supply tank I60 for carbon, dioxide will be opened and reducing valve IOI willbe set to give the deplate 00b and its other end secured to member 00. p In Fig. 9 a diagram is shown illustrating the H circuits and connections used ln'Figs. 4 tell above described. Motor H0 is shown and conductors I20 are illustrated as connected to a suitable source of current'such as a battery I30. Galvanometer 00 is shown and conductors Iii and I32 also shown in Fig. 5 extend from theterminals of said galvanometer to conductors 00 within the chamber formed by the wall I00. It will be understood that only a portion of the wall I30 is shown but that said wall will be con-' tinuous and encloses room or closed chamber in which the apparatus shown in Fig. 3 except portions 20, 22, 14 and 10 will be disposed. Needle pointer lid is shown as is member 00 and sleeve 84. Lever I20 is shown'as; isa part of member 00 which carries contacts 01 and :00. Members I04 and I00 are shown and members I" and I00 which carry contacts I00 and H0 are shown. Contact 01 has connected thereto a conductor I30 which extends to a source of current I30. A conductor I31 connects to'source of current or battery I00, the same having therein a switch I38 and said conductor I 31 extends to one winding I40a of a relay I40, said winding being of rather high resistance. Another conductor I4I extends from the other end of windsired pressure for delivery 01' carbon dioxide through conduit I41 'into the chamber. Switch Ill and switch I5I will be closed and motor II will be operated. Contacts 91 and 98 are normally engaged. With said contacts'engaged a current will now flow from sourcefof current I00, through contacts 01 and 00, through conductor I, through winding I40a, throughswitch I30 and back to source I". The winding I40a does not exert sufllcient magnetic pull or force to move armature I40c against the tension of spring I40. Contacts I40e and I44 thus remain engaged. Contacts I00 and Ill are-fnormally separated so that no current is flowing through winding I40b. With contacts I40e and I44 engaged and switch III closed current flows through valve I46 so that this valve is opened and'carbon dioxide is thus discharged through conduit I41 into the chamber. revolved and while the period of rotation could be determined as desired. in practice this disk has made one revolution'every minute. At each revolution of disk I20 pin II4 engages lever arm 125a, swinging lever I20 and moving arm I2lib against roller I02. This swings member about its pivot 00 and spring arm 00 at its upper portion 00a pushes against member I04 swinging it about its pivot I04b. With an atmosphere of air in the chamber the needle 8i will occupy a normal position so that pointer 8Ia registerswith zero on scale 02. As the proportion of carbon dioxide in the atmosphere increases due to the supplying of the same through conduit I41 the resistance in tube 1I through conductor 12 is varied and needle al is moved, the same mov- With motor no running disk mis' it engages abutment member ll so that further movement of member I is prevented. The balance of the movement of member I must'there- Idle and separate contacts Ille and I.

fore be accommodated by the flexingofarrn ll and thisseparates contacts" and II. This has no effect on relay ill and the circuit through valve I remains closed and carbon dioxide is thus discharged into the chamber. When needle I II is sumciently deflected by the percentage of carbon dioxide in the chamber it moves over so thatit will be between member I" and abutment ll. Whenme'rnber ll is swung and bushing I4 is notbeween member Ill and abutment II, there is no resistance to the swingingmovement i member or segment Ill and it can be swung without any change in the relation of contacts I and III which are normally separated.

When'sleeve ll, however, by suflicient deflection of needle II moves into alinement with member ill the swinging movementoi member III will be prevented in part as shown in Fig. 8 and mernwinding Illb and to source I through conductor Ill. The winding "0b is of rather low resistance and suflicient magnetic pull or force is now exerted by relay Ill to attract armature When contacts I and ille. are-separated the circuit through valve I is opened and I said valve closes, shutting oi! the supply of carbon dioxide to the chamber within wall I". After bushing.

ll has moved into alinement with segment or member Ifll. it of courseis out of alinement with member or segment I. It therefore oilers no resistance to thernovement of member Ill but spring arm 9! and member I can move with arm. ll so that said'arr'n will not be flexed and .contacts I1 and 8! will not be separated. Said contacts therefore remain engaged and with and will remain cut oil! until the percentage decreases and more carbon dioxide is needed to maintain the desired percentage. The amount or percentage of carbon dioxide is in eifect checked everytime the disk I" makes a revolution. As stated, in the practical use of the spparatus this period was substantially one minute. Instead of using the bridge illustrated in Fig. 3 in the chamber a bridge such as shown in Fig. 10 could be used. In this structure conductor- I10 is connected to one end of the bridge and to a suitable source of current "I. A conductor I12 having an ammeter I13 inserted therein extends from source "I to a resistance I14. A movable or adimtable contact I" cooperates with resistance I14 to form a rheostat and a conductor I18 extends from contact! to-the otherend of the bridge. Tubes or cells I11 are disposed on one side of the bridge and tubes or cells I1! are on the other side. The tubes I18 are sealed and will contain air. Tubes I11 have walls of screen material so that the atmosphere of the chamber can pass therethrou'gh; In both .cells I11 and I" aflne wire of platinum or other suitable metal I110 and Illa forms the conductor through the cell. A current willflow through said nne wire and the heat generated in the wire will beconducted away from the wire at a diflerent rate in the tubes I11 than in the tubes I10. This diflerence will increase as the zvercenisge 01' carbon dioxide decreases in the chamber. Conductors I extend from each side of the bridge at the central portion thereof, one

two of the cells or tub es I11- are used. The galarmature illc'pulled'up there is enough magnetic pull in relay Ill to hold said armature pulled up so as to keep contacts Idle and I separated. As long as needle II is sufliciently deflected to keep sleeve, 84 in alinement with member I" the supply of carbon dioxide will therefore be discontinued. Should the percentage of carbon dioxide, however. decrease in the chamberheedle II will move back and when I reengage contacts Ille and I.

it moves suiliclently to come into aiinement with member I contacts l1 and I! will be separated In the rotation of disk I23 so that the circuit through winding Illa will be broken. Contacts :I and III will be separated when sleeve .4

moves out of alinement with member I" and spring I" will then move armature 0c and will thus be seen that carbon dioxide will be supplied to the chamber until the desired percentage has been reached. when this percentage has been reached the suppl will be cut oil vanometer' will be deflected in direct ratio to the percentage of carbon dioxide in the atmosphere.

From the above description it is seen that applicant has provided a simple and eflicient methed and several emcient forms of apparatus for regulating and maintaining an atmosphere in the chamber having a desiredpercentage of carbon dioxide ,therein. Such a chamber is now used as a storage chamber for articles or food.

air or some still lighter gas are used in the regulation. The difference in the light transmitting properties of the gases might be utilized by the use of an interferometer. The apparatus used is quite sensitive, yet it is very accurate and the percentage of carbon dioxide can be controlled within very small limits. The articles of food can thus be kept in the storage chamber with assurance that they will be well preserved. An

The circuit will excessive amount of carbon dioxide is injurious to most of the products so that it is quite essential that a dependable regulation must be had so that suiiicient carbon dioxide can be maintained in the atmosphere and yet an excessive amount prevented. The form of apparatus disclosed in Figs. 4 to 10 is well suited for use on refrigerator cars. There are no parts the operation of which would be prevented by movement of the cars. The method and apparatus have been demonstrated in actual practice and found to be very successful and eilicient.

This application is a continuation in part of an electrical instrument including a moving in the steps and sequenceof stepsoi the method without departing from the scope of applicants invention, which, generally stated, consists in a method and apparatus capable of carrying out the objects. above set forth, such as disclosed and defined in the appended claims.

What is claimed is: r

l. A control apparatus for. causing agas to be fed into a chamber containing a second gas hav- 7 ing physical properties difi'erent iromthe physical properties of said first mentioned gas and for establishing and maintaining a gaseous content in said chamber consisting of said gases and including a predetermined quantity of said first mentioned gas, comprising a mechanism capable of operation to, cause the flow of said first mentioned gas from a source of supply into said chamber until said chamber contains said predetermined quantity of said first mentioned gas, an electrical instrument including .a movin member adapted to be actuated'to a plurality of diiierent positions in response to alteration oi the physical properties of said gaseous content in said chamber, as caused by the presence of difierent quantities of said first mentioned gas, in-

cluding a position for said moving member corresponding to a gaseous content in said'chamber containing said predetermined quantity of said first mentioned gas, an abutment member. adjacent which said moving member travels, an ad- Justable member adJacent and at the opposite side of the path of said moving member, means including a pair of electrical contacts for moving said adjustable member against said moving 1 member to press the sameagainst said; abutment member. said contacts being relatively moved by the action of said means whereby when said moving member is in said position and in the path of said adjustable member said contacts will control said'mechanism' toshut off the supply of said first mentioned gas.

2. 'A control apparatus for causing a gasjto be fed into a chamber containing a second. gas having physical properties diflerent from the physical properties of said first mentioned gas and for establishing anclv maintaining a gaseous content in said chamber consisting oi said gases and including a predetermined quantity of said, first mentioned gas, comprising a mechanism capable of operation to cause the flow of said first mentioned gas from a, source of supply into said member adapted to be actuated to a plurality of difierent positions in response to alteration of the physical properties of said gaseous content in said chamber as caused by the presence of diflerent quantities of said first mentioned gas, including a position for said moving member corresponding to a gaseous content in said chamber containing said predetermined quantity of said first mentioned gas, an electrical circuit for controlling said valve including an electro-magnet, a movable means adjustable to different positions along the path of travel of said moving member and movable transversely of said path to engage said moving member when aligned therewith, (a pair of normally separated contacts carried by said means and relatively moved to be closed when said means engages said moving member to close said circuit, energize said magnet and cause closure of said valve, a motor driven means for moving said means transversely of said path at regular small intervals.

3. A control, apparatus for causing a gas to be led into a chamber containing a difierent gas ,and iorestablishing and maintaining a gaseous content in said chamber consisting of said first mentioned gas and said different gas and including a predetermined quantity of said iirst mentioned gas comprising a source of supply of said gas, conduit means connecting said source of supply and said chamber, valve means for controlling the flow of said firstmentioned gas from said source of supply into said chamber and means for regulating said valve means to cause how of said first mentioned gas into said chamber until said chamber contains said predetermined quantity of said first mentioned gas and to cause said supply of gas from said chamber to be discontinued when said chamber is made to contain said predetermined quantity of said first mentioned gas, comprising a moving member movable in accordance with the proportion of, said first mentioned gas in said chamber, a

motor actuated movable member movable across thepathof said moving member at regular short intervals, a pair of electrical contacts for controlling said valve relatively moved when said moving member comes into the path of said movable member and is engaged thereby to cause closure of said valve and discontinue the supply of said first mentioned gas.

HERVEY H. BARBER. 

